This study intends to establish human plasma cell lines derived from patients with multiple myeloma and to use these cells for various immunological, growth kinetics, and pharmacological investigations. Bone marrow aspirates and biopsies from plasma-cytomas will be grown utilizing different nutrients and culture vessels. Growth kinetics parameters will be defined by conventional techniques and compared to similar data obtained simultaneously in vivo. Cell lines will be characterized in terms of morphology, Ig production, karyotype, etc. Immunological investigations will use these cells to define cell mediated and humoral responses. The effect of chemotherapeutic drugs at the cellular level will be studied by the colony-formation technique and by pulse cytophotometry.